ABSTRACT
A simulation of competitively primed allele-specific DNA amplification has been constructed and its behavior examined. This has shown that when the ratio of the amount of homoduplex misprime product to the total amount of amplimer is low, it increases by approximately one-fourth of the mispriming frequency with each doubling of the total amount of amplimer. When the ratio is high and reverse mispriming becomes significant, it asymptotes toward a value <0.5. An analogous simulation was carried out on conventional allele-specific DNA amplification. As expected, the ratio of the amount of amplimer in the positive and negative reactions closely approximates the mispriming frequency provided that amplification is exponential in both cases. This suggests that conventional allele-specific amplification has somewhat higher inherent specificity than competitively primed amplification. However, conventional allele-specific reactions are subject to a "catch-up" phase in which the positive reaction slows or stops, thus reducing the specificity. It was hypothesized that competitively primed reactions may be easier to optimize than conventional allele-specific reactions. This conjecture was supported experimentally. In addition, it was shown that the specificity of competitively primed reactions is a function of the degree of amplification.
Subject(s)
Alleles , Polymerase Chain Reaction/methods , Binding, Competitive , Computer Simulation , DNA Primers/genetics , Models, Genetic , Reproducibility of Results , Sensitivity and Specificity , Substrate SpecificityABSTRACT
A neoplasm of unknown origin in cervical and axillary lymph nodes was diagnosed as anemone cell tumor by ultrastructural examination. Three years after the initial diagnosis of anemone cell tumor, a high-grade transitional cell carcinoma of the bladder was discovered. The results of immunoperoxidase staining of the cervical lymph node, axillary lymph node, and bladder tumors for keratin, carcinoembryonic antigen, and human chorionic gonadotropin (HCG) strongly suggest that the anemone cell tumors in this case represent metastases of bladder carcinoma cells capable of producing HCG.
